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Error Code P0469 is defined as Purge Flow Sensor Circuit Intermittent. This means the Evaporative (fuel) system is having a problem with the purge flow sensor, often caused by a damaged charcoal canister or malfunctioning flow sensor.
This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II, especially those made from 1996 up to the present day. It is, however, more common among Mercedes vehicles. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
Error Code P0469 means there’s a problem with the evaporative (fuel) system, and that a component of the system is now working correctly. This may or may not be caused by a problem in the purge flow sensor or solenoid. It could also be caused by a number of other system components failing, such as the gas cap, charcoal canister, flow sensor, fuel line, vacuum line, or fuel vapor hose.
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. However, there may be other codes stored in the PCM of the vehicle as well, which would have their own set of symptoms.
Modern Evaporative system is complex, as it comes with multiple components working together. Thus Error Code P0469 can be caused by different problems, such as:
- Defective purge control solenoid
- Clogged or damaged charcoal canister
- Cracked vacuum hose
- Defective pressure sensor
- Defective flow sensor
- Cracked or defective fuel vapor hose
- Loose or improperly installed gas cap
- Failed PCM (rare)
How to Check
Diagnosing Error Code P0469 can be tricky; technicians usually start their diagnosing by reading all the codes stored in the vehicle’s PCM so they can come up with an informed decision based on codes present other than the P0469. Next, technicians will clear the codes and then take the vehicle for a test drive to determine if the code reset.
Then, the mechanic will inspect the gas cap to ensure it is properly installed and don’t have any damage. Next, they inspect the connections and the wirings, followed by inspection of the charcoal canister. They can also use a smoke machine to test the vacuum and fuel vapor lines for damages.
Lastly, technicians will check the operation and all components in the purge control solenoid/
Diagnosing EVAP codes can require multiple test drives, as it usually takes several test drive cycles for the codes to reset in the computer.
How to Fix
Since the error code affects the EVAP system which is composed of multiple parts, repairs for this code vary widely, as there is usually no single underlying cause in all instances. Thus, repairs should hinge through in-depth and accurate diagnosis to pinpoint the cause of the problem.
Common repairs include:
- Proper installation or replacement of the gas cap
- Repair or replacement of the connectors and wirings
- Repair or replacement of clogged charcoal canister
The most common mistake in repairing this code is replacing parts without actually diagnosing the underlying issue. Often, this process starts by replacement of the gas cap and then followed by replacement of other components down the line if the code returns.
Depending on the underlying problem, this code may not be a serious issue. Minor problems can be caused by incorrectly installed or faulty gas cap. For other instances that result in limited supply on the engine, however, this code can leave the vehicle unable to be driven.